The present invention relates to a device and a process for carrying out tests and/or analyses of fluids, notably with a view to determining blood groups or performing compatibility tests. In particular, it relates to a device and a process which make it possible to carry out safe tests and analyses of fluids under simple and safe conditions, which make these tests and analyses particularly attractive.
This device and process are particularly suitable for carrying out tests and analyses without any contamination by or of the environment.
The invention relates quite particularly, but not exclusively, to a device and a process for determining blood groups, notably in connection with a blood transfusion, by a visual test in the presence of a reagent.
Several types of devices are already known in the art for determining a patient's blood group or for carrying out blood compatibility tests.
Thus, EP-A-0,054,087 describes an apparatus for testing fluids deposited in layers on supports, capable of imparting a centrifugal force to said fluids, to which is applied an appropriate antibody, in order to reveal the antigen-antibody compatibility. This apparatus is complicated to manufacture and manipulate. It requires control by an outside energy source.
EP-A-0,104,881 describes a device for transfusion compatibility tests designed to be used at the bedside of a patient who is to receive a transfusion. This device can be fixed to the blood bag, and receives, by capillarity, a specified quantity of the patient's blood, which is then contacted with an antiserum. The porous plastic member in which this capillarity is exerted should be such that only non-agglutinated blood can continue to migrate by capillarity. Such a member, which consists of an absorbent porous material, is not protected before being introduced into the blood-group-revealing antiserum.
French Patent A-2,586,815 describes a device for the determination of a blood group, comprising, for visual examination of a mixture of blood sample and test serum, at least one closed chamber and means for introducing the blood specimen into said chamber. Means are provided to evacuate the air from the chamber through a permeable hydrophobic membrane, in order to permit the specimen to penetrate thereinto without being opposed by an excess pressure of air. The blood from the receiver is injected by a syringe.
Document WO-A-85/05039 describes a test-tube holder comprising a vacuum-creating system, wherein the tubes containing samples to be tested have a plug at their upper end and an elastic stopper at their base designed to be perforated by a hollow needle. A partial vacuum is then created in the tubes. The total content of each tube is thus extracted in one operation, without the possibility of partial or repeated extractions.
Document WO-A-92/08988 discloses a complex and automated apparatus for taking liquid test samples and simultaneously cleaning the sampling system of test samples. This system comprises a serum loading station, a detection station, an index table for regulating the advance of the tubes toward a collection station, a station for sampling aliquot parts and a wash station. Here again, the sampling is done by means of a needle whose point is introduced into the respective tube, and a vacuum is then applied to the needle, by which the liquid is completely extracted from the tube.
Document WO-A-87/01461 describes a device for determining a blood group, wherein means make it possible to insert a blood sample to be tested and/or the test serum in a closed chamber where the reaction of the test serum with the blood is observed. In practice, a moving member such as a hollow needle effects the transfer, to the chamber, of an amount of blood determined by the degree of partial vacuum or negative pressure previously created in said chamber. More preferably, the device comprises a housing made of two parts each displaceable relative to the other and each displaceable relative to the needle, which then has two points perforating, respectively and successively, the wall of the sample receptacle and that of the chamber.
None of the prior art testing devices fully satisfies all the conditions currently required for such devices, such as optimum conditions of reliability, manageability and safety, particularly in the area of blood group determination, notably during blood transfusions.
The problems most frequently encountered during control tests and analyses in all areas consist, in fact, of the risks of pollution of the substance to be analyzed and of the risks of staining or contamination of the operator. On the other hand, the impossibility of preserving the reactions in time prevents storage of previously obtained results.
More particularly in the medical domain, the possibility of viral contaminations could sometimes make it awkward, even dangerous for the manipulator to do a blood compatibility check just before a transfusion, a check consisting in verifying the correlation between the patient's blood (recipient) and that contained in the blood bag (donor) designed to be transfused into the patient. In practice, the currently available devices do not offer all the advantages that are expected in this regard. Nor do they provide total safety with regard to the assignment of the results and their follow-up.
Hence a need existed for a reliable, safe and easily manipulable device for performing control tests and analyses, a device which can be used in all areas and particularly in human and veterinary biology.
It has now been found, unexpectedly, that these advantages, as well as others which will become more obvious on reading the following description, are offered by a device and process according to the present invention.